Method of and means for commencing a deforming operation, e.g., hydrostatic extrusion of a billet

ABSTRACT

A plurality of lengths of material of varying hardness is arranged in order of hardness and the lengths are pressure welded to each other at planar joints to form a composite billet having a forward end and a rearward end, the hardness of the composite billet increasing from the forward end toward the rear end thereof and not exceeding the hardness of the main billet. To abate or eliminate abrupt changes in hardness, the cross section of the composite billet, initially larger than that of the main billet, is reduced to the same cross section as the main billet to spread the pressure welded joints. The rearward end of the reduced composite billet is pressure welded to the forward end of the main billet and serves as a billet nose which is deformed prior to deformation of the main billet.

United States Patent 1 Fuchs, Jr. et a1.

[54] METHOD OF AND MEANS FOR COMMENCING A DEFORMING OPERATION, E.G., HYDROSTATIC EXTRUSION OF A BILLET [75] Inventors: Francis Joseph Fuchs, Jr.,'Princeton Junction; Peruvemba Swaminatha Venkatesan, Princeton, both of NJ.

[73] Assignee: Western Electric Company,

Incorporated, New York, NY.

[22] Filed: June 22, 1972 [21] Appl. No.: 265,165

[ Oct. 23, 1973 Primary ExaminerRichard J. Herbst Att0rneyW. M. Kain et a1.

[57] ABSTRACT A plurality of lengths of material of varying hardness is arranged in order of hardness and the lengths are pressure welded to each other at planar joints to form a composite billet having a forward end and a rearward end, the hardness of the composite billet increasing from the forward end toward the rear end thereof and not exceeding the hardness of the main billet. To abate or eliminate abrupt changes in hardness, the cross section of the composite billet, initially larger than that of the main billet, is reduced to the same cross section as the main billet to spread the pressure welded joints. The rearward end of the reduced composite billet is pressure welded to the forward end of the main billet and serves as a billet nose which is deformed prior to deformation of the main billet.

6 Claims, 3 Drawing Figures ..M ii I A v 9 I 4 i A 1 EQFA METHOD OF AND MEANS FOR COMMENCING A DEFORMING OPERATION, E.G., HYDROSTATIC EXTRUSION OF A BILLET BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates, generally speaking, to improved method of and means for commencing an extrusion or drawing operation. Specifically, this invention relates to method and means for eliminating or substantially reducing peak effort ordinarily required to initiate an extrusion or drawing operation. More specifically, this invention relates to method of and means for eliminating or substantially reducing peak pressure heretofore encountered in commencing hydrostatic extrusion.

2. Description of the Prior Art Various methods and means for drawing or extrusion, including hydrostatic extrusion, are now well known. See, for example, U. S. Pat. No. I 3,667,267 which teaches method and apparatus for continuously hydrostatically extruding an elongated billet for indefinite length to produce wire of indefinite length.

In commencing hydrostatic extrusion of certain materials to obtain certain ratios of reduction, it has been noted that, when the nose of the billet enters and initially contacts the zone of deformation of the die, the pressure of the extrusion fluid rises to a peak value'until extrusion commences. After extrusion commences, the pressure of the extrusion fluid falls to a lower, substantially constant, level known as the run-out pressure. This, in the hydrostatic extrusion of copper at reduction ratios greater than 20, there is always a peak pressure at the commencement of extrusion which is greater than the run-out pressure.

Although the peak pressure occurs only at the commencement of an extrusion operation, thepressure vessel for containing the extrusion operation, the die, die stem and related components must be designed to withstand this peak pressure which may, in some instances, be as much as 25 percent or more above run-outpressure, even though virtually the entire extrusion opera tion is performed at the lower-run-out pressure. Thus, for virtually the entire extrusion operation, the pressure vessel, die, die stem and related components are oven designed by as much as 25 percent or more. From another point of view, elimination or substantial reduction of peak pressure permits much higher (e.g., by an order of magnitude or so) ratios of reduction in equipment of a given design and pressure capability. Indeed, for certain materials, ratios of reduction are now attainable which heretofore were not attainable because of design limits on maximum pressure of-equipment.

An example of the relationship between peak pressure and run-out pressure can be seen inthe hydrostatic extrusion of a 0.300 inch diameter copper billet to produce 0.013 inch diameter wire, representing a reduction ratio of 500, wherein the peak pressure in the extrusion fluid is 370,000 psi and the run-out pressure in the extrusion fluid is 280,000 psi.

Moreover, as peak pressure is reached, extrusion commences with a burst of speed, which may be undesirable.

In non-hydrostatic extrusion operations, and also in drawing operations, it has been noted that, for certain materials and for certain ratios of reduction, the initial effort required to commence the extrusion or drawing operation is substantially in excess of the effort required to maintain the extrusion or drawing operation, and, further, with conventional billets, the extrusion or drawing operation may commence with an undesirable burst of speed.

Efforts have been made in the past to facilitate the extursion of billets. In U. S. Pat. No. 2,630,220 (1953) to Sejournet, extrusion of 'a hot billet or ingot of steel is commenced by interposing between the front endof the hot billet and the die a packet of glass fibers and glass plate, the glass melting under the heat of the billet and lubricating the die. In U. S. Pat. No. 3,345,842 (1967) to Richards, a hot billet is coated with a plurality of layers of glass of different viscosity-temperature characteristics (e.g., by sequentially dipping the entire hot billet into tanks of the various molten glasses) and is then extruded through a die.

In each of the above instances, the molten glass acts as a lubricant.

SUMMARY OF THE INVENTION One of the objects of. this invention is to provide improved method of and means for commencing an extrusion or a drawing'operation.

Another of the objects of this invention is to provide improved method of and means for eliminating or substantially reducing peak effort ordinarily required to initiate an extrusion or drawing operation.

Still another of the objects of this invention is to provide improved method of and means for commencing a hydrostatic extrusion operation.

Yet another of the objects of this invention is to provide method of and means for eliminating or substantially reducing peak pressure in hydrostatic extrusion.

A further object of this invention is to provide method of and means for smoothly commencinghydrostatic extrusion.

Still other and further objects of this invention will become apparent during the course of the following description and by reference to the accompanying drawings and appended claims.

Briefly, we have discovered that the foregoing objects may be attained by pressure welding a'series of short billets of varying degrees of hardness to each other and to a short length of billet of the same material as the main billet to be deformed (e.g., by extrusion), the short billets being arranged according to their respective hardnesses so as to provide a composite billet having hardness decreasing stepwise from the rearward end of the composite billet (i.e., that end of the composite billet defined by the billetof the same material as the main billet).to the forward endthereof. The cross section (e.g., diameter) of the composite billet-is somewhat larger than thecross section (e.g., diameter) of the main billet. Thereafter, the composite billet is given a small reduction in cross section which then substantially equals thecross section ofthe main billet, of indefinite length in the illustrated embodiment, thereby to spread the essentially planar pressure welded interfaces between the short billets so as to eliminate or sub stantially reduce abrupt changes in hardness along the reduced composite billet. The rearward end of the reduced composite billet, now termed a billet nose, is then pressure welded to the forward end of the main billet, and the main billet with billet nose is deformed (e.g., by extrusion) to produce the final product.

BRIEF DESCRIPTION OF THE DRAWINGS Referring now to the drawings in which like numerals represent like parts in the several views:

FIG. 1 represents an idealized plot of deformation effort (e.g., hydrostatic extrusion fluid pressure) vs. time for two conditions, vis., deformation (e.g., hydrostatic extrusion) with an ordinary billet, and deformation (e.g., hydrostatic extrusion) with a billet nose prepared according to the present invention.

FIG. 2 represents a longitudinal view of a composite billet prepared according to the present invention. For comparison of the relative diameters of the composite billet and the main billet to be extruded, the outline in phantom of the main billet is shown.

FIG. 3 represents a medial longitudinal section of hydrostatic extrusion apparatus as disclosed in U. S. Pat. No. 3,667,267 and shows a billet nose, of a main billet, which has just engaged the zone of deformation of the die and which has not yet commenced to extrude, the said billet nose having been prepared by giving the composite billet of FIG. 2 a small reduction in cross section to spread the pressure-welded joints.

DESCRIPTION OF THE PREFERRED EMBODIMENT In commencing the hydrostatic extrusion of conventional billets (e.g., rods of indefinite length) of certain materials to achieve certain ratios of reduction, when the nose of the billet enters and initially contacts the zone of deformation of the die, and until extrusion of the billet through the die commences, the pressure of the extrusion fluid rises generally along curve 1 of FIG. 1 and reaches a maximum value 2. When the billet begins to extrude through the die, the pressure of the extrusion fluid decreases, generally along curve 3, to a lower substantially constant level 4 known as the runout pressure.

The difference between the maximum or peak pressure 2 and the run-out pressure 4 requires that the pressure vessel for containing the extrusion operation, the die, die stem and related components be overdesigned for this high transitory condition.

The present invention eliminates or substantially reduces this peak or maximum pressure 2, and permits the extrusion apparatus to be designed to operate substantially under the conditions of run-out pressure.

An extrusion billet 5, shown in the illustrative embodiment as a rod of indefinite length and having fastened to the forward end thereof a billet nose 6 prepared according to the present invention, is shown in FIG. 3, prior to the actual commencement of extrusion and at the point of initial contact with the zone of deformation of die 7 of extrusion apparatus 8 of the type described in U. S. Pat. N0. 3,667,267. Extrusion apparatus 8 forms no part of the present invention and reference to U. S. Pat. No. 3,667,267 should be made if a detailed description of the construction and operation and billet 10 is of the same hardness, and preferably of the same material as billet 5.

Advantageously, the shear strength of billet 13 is approximately percent of the shear strength of billet 12, the shear strength of billet 12 is approximately 80 percent of the shear strength of billet 11, and the shear strength of billet 11 is approximately 80 percent of the shear strength of billet 10. i

It will be noted that interfaces 14, 15 and 16 lie essentially in a plane transverse to the longitudinal axis of composite billet 9. Under some circumstances, and with certain materials, if composite billet 9 were to be mounted to the forward end of billet 5 and extruded, the changes in hardness of short billets 10, ll, 12 and 13 at interfaces 14, 15 and 16 might be too abrupt and might, therefore, cause peaks as shown at 2 in FIG. 1.

To overcome the problem mentioned in the preceding paragraph, composite billet 9, shown as a rod, is reduced in cross section through a preliminary drawing or extrusion operation sufficiently to spread the heretofore essentially planar pressure welded interfaces 14, 15 and 16 to form pressure welded regions 14a, 15a and 16a having longitudinal dimension, interposed between short billets 10, 11, 12 and 13. Pressure'welded regions 14a, 15a and 16a consist of a mixture of material of the short billets between which they are interposed and have hardnesses intermediate the hardnesses of the said short billet between which they are interposed. The preliminary drawing or extrusion operation is sufficient to cause the desired degree of spreading of interfaces 14, 15 and 16 but yet is not so severe as to result in peaks of the type shown in FIG. 1. Because the diameter of the preliminarily reduced composite billet 9, nowtermed a billet nose 6, is substantially the same as that of extrusion billet 5, it will be apparent that the initial diameter of composite billet 9 should be somewhat greater than that of billet nose 6 and hence of billet 5. For example, the diameter of a typical wire extrusion rod is inch; advantageously, the diameter of composite billet 9 will be 1% inch and its reduction to inch diameter to form billet nose 6 will adequately spread pressure welded interfaces 14, 15 and 16.

Billet nose 6, prepared as hereinabove described, has I a rearward end 17 defined by short billet 10 of the same hardness and preferably the same material, as billet 5, and has a forward end 18 which may be provided with a male conical profile to substantially match the profile of die '7.

The rearward end 17 of billet nose 6 is pressure welded to the forward end of billet 5 and the operation of extruding the said billet 5 may now be'commenced. With billet nose 6 mounted to the forward .end of billet 5, the pressure of the extrusionfluid rises generally along curve 1 of FIG, 1 until extrusion of the forward and thence along curve 19as the various short billets constituting billet nose 6 extrude, until short billet l0 commences to extrude, at which point the pressure of the extrusion fluid proceeds along curve 4 representing the run-out pressure for billet 5. There is a complete elimination of pressure peak in the extrusion fluid as represented by point 2 of FIG. 1, and the extrusion of billet 5 commences smoothly. Consequently the vessel for containing the extrusion operation, the die, die steam and related components need be designed only to withstand the run-out pressure 4 and not a transitory maximum or peak pressure 2.

It will be understood that composite billet 9 may include more or less than the four short billets shown in FIG. 2.

In the foregoing description of the preferred embodiment, the value of the present invention has been illustrated in a hydrostatic extrusion environment. The present invention is capable of reducing the effort required to initiate non-hydrostatic extrusion and drawing operations smoothly and without initial peaks in the effort required for such operations.

What is claimed is:

1. Method of commencing deformation against a deforming agency of a main billet having a forward end, said method comprising:

a. securing a plurality of lengths of materials of varying hardness together at essentially planar joints to form a composite billet having a forward end and a rearward end with hardness increasing from said forward end toward said rearward end and not exceeding the hardness of said main billet;

b. reducing the cross section of said composite billet to spread the joint between adjacent lengths;

c. securing the rearward end of said reducedcomposite billet to the forward end of said main billet;

d. advancing the main billet and the reduced composite billet against the deforming agency to deform the reduced composite and then the main billet.

2. Method as in claim 1, wherein:

e. the said lengths of materials are secured to each other by pressure welding,

f. the rearward end of the composite billet is secured to the forward end of the main billet by pressure welding,

3. Method as in claim 1, wherein:

e. the cross section of the composite billet is larger than the cross section of the main billet,

f. the cross section of the reduced composite billet is essentially the same as the cross section of the main billet.

4. Method as in claim 1, wherein:

e. the jointsbetween adjacent lengths are transverse to the longitudinal axis of the composite billet.

5. Method as in claim 1, wherein:

e. that length of said plurality of lengths at the rearward end of said composite billet is of the same hardness as the main billet.

6. Method as in claim 1, wherein:

e. that length of said plurality of lengths at the rearward end of said composite billet is of the same material as the main billet.

UNITED STATES PATENT I OFFICE QERTEHATE QF 0RRECTION p No. 3,766,766 Dated October 23, 1973 FRANCIS JOSEPH FUCHS, JR.-PERUVEMBA swAMINATHA VENKATESAN Case 9o-o it is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

[ Title page, column 2, "Attorney W. M. Kain et al." should 1 read --Attorney Jack Schuman-- (only) Column 1, line 23, "for" should read --of--; line 33, "This," should read --Thus,--

Column 2, line '8, "extursion" should read "extrusion".

Column 3, line 7', "vis.," should read viz.,-; line 56, "NO," should read -No.--5 line 66, "then" should read -than--.

Column L, line 67, "steam" should read --'stem--.

Column 6, 7 claim 1,- line 2, "reduced composite-and" should read --reduced composite billet and--; claim 2, line 8, "Welding," should read -,-Weldi'ng.--.

Signed and sealed this 19th day of March 1974."

(SEAL) Attest:

EDWARD M.IFLETCHER,JIR. c. MARSHALL DANN Attesting Officer Commissioner of Patents 

1. Method of commencing deformation against a deforming agency of a main billet having a forward end, said method comprising: a. securing a plurality of lengths of materials of varying hardness together at essentially planar joints to form a composite billet having a forward end and a rearward end with hardness increasing from said forward end toward said rearward end and not exceeding the hardness of said main billet; b. reducing the cross section of said composite biLlet to spread the joint between adjacent lengths; c. securing the rearward end of said reduced composite billet to the forward end of said main billet; d. advancing the main billet and the reduced composite billet against the deforming agency to deform the reduced composite billet and then the main billet.
 2. Method as in claim 1, wherein: e. the said lengths of materials are secured to each other by pressure welding, f. the rearward end of the composite billet is secured to the forward end of the main billet by pressure welding.
 3. Method as in claim 1, wherein: e. the cross section of the composite billet is larger than the cross section of the main billet, f. the cross section of the reduced composite billet is essentially the same as the cross section of the main billet.
 4. Method as in claim 1, wherein: e. the joints between adjacent lengths are transverse to the longitudinal axis of the composite billet.
 5. Method as in claim 1, wherein: e. that length of said plurality of lengths at the rearward end of said composite billet is of the same hardness as the main billet.
 6. Method as in claim 1, wherein: e. that length of said plurality of lengths at the rearward end of said composite billet is of the same material as the main billet. 